The invention relates to devices for moving samples axially and in rotation in an evacuated enclosure. It is usable particularly for moving specimens in enclosures in which a high degree of vacuum exists, for example, in spectroscopy devices, where a vacuum of about 10.sup.-11 torr is necessary.
It is difficult to render seals between mutually movable elements and particularly sliding seals perfectly air-tight. When practically sealing of a transmission mechanism is necessary, recourse has consequently been had in the past to a magnetic drive. This type of drive has the drawback of not being positive: slippage can occur and render impossible the direct determination of the axial and angular position of the sample from the movements imposed on the actuating members. The use of magnets cannot be consiliated with the need of heating the parts to a high temperature for degasing.
One solution which appears a priori interesting, consists of using a sample-holder rod which sealingly projects through the bottom wall of sealing bellows coaxial with the direction of axial movement and is fixed thereto. In practice, this solution is no longer applicable when the amplitude of the movements is large, since it would require bellows which are much too long. Movements of more than one meter are often necessary for spectrometry.